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Lightspeed Attenuator - Best Preamp Ever?

The question is a bit rhetorical. No preamp is the best ever, and much depends on system context. I am starting this thread beacuase there is a lot of info on this preamp in a Music First Audio Passive...thread, an Slagle AVC Modules...thread and wanted to be sure that information on this amazing product did not get lost in those threads.

I suspect that many folks may give this preamp a try at $450, direct from Australia, so I thought it would be good for current owners and future owners to have a place to describe their experience with this preamp.

It is a passive preamp that uses light LEDs, rather than mechanical contacts, to alter resistance and thereby attenuation of the source signal. It has been extremely hot in the DIY community, since the maker of this preamp provided gernerously provided information on how to make one. The trick is that while there are few parts, getting it done right, the matching of the parts is time consuming and tricky, and to boot, most of use would solder our fingers together if we tried. At $450, don't bother. It is cased in a small chassis that is fully shielded alloy, it gets it's RF sink earth via the interconnects. Vibration doesn't come into it as there is nothing to get vibrated as it's passive, even the active led's are immune as they are gas element, no filaments. The feet I attach are soft silicon/sorbethane compound anyway just in case.

This is not audio jewelry with bling, but solidly made and there is little room (if any) for audionervosa or tweaking.

So is this the best preamp ever? It might be if you have a single source (though you could use a switch box), your source is 2v or higher, your IC from pre-amp to amp is less than 2m to keep capaitance low, your amp is 5kohm input or higher (most any tube amp), and your amp is relatively sensitive (1v input sensitivity or lower v would be just right). In other words, within a passive friendly system (you do have to give this some thought), this is the finest passive preamp I have ever heard, and I have has many ranging form resistor-based to TVCs and AVCs.

In my system, with my equipment, I think it is the best I have heard passive or active, but I lean towards prefering preamp neutrality and transparency, without loosing musicality, dynamics, or the handling of low bass and highs.

If you own one, what are your impressions versus anything you have heard?

Is it the best ever? I suspect for some it may be, and to say that for a $450 product makes it stupidgood.
pubul57
georgehifi's avatar
georgehifi
10,312 posts
 
It would be good for someone to grab an ohm-meter and measure the input terminals (Amp off naturally).
If it is bipolar transistor input you can bet you life it's going to be less than 47k.
If it's fet transistor input there's a chance it's 47k, maybe higher.
If there is no reading or wavering all over the place it has capacitor coupled input (yuck and double yuck)
Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
Banquo363 As stated in the instructions, you can leave it powered 24/7 just leave the volume at half position when not playing music. If using battery supply this is not possible, but still you can plug in the wall wart and leave it on 24/7 and you can change over to the battery even while playing music just pull out the wall wart plug and insert the battery plug quickly, no bangs or crashes.
Cheers George
fiddler
581 posts
 
Banquo,

Your experience mirrors mine. If you look back in this thread, I originally posted that my Supratek bettered the LSA in my system during my initial trial period, which as I recall, was a rather short audition. I later gave the LSA another chance after reading how many mega-dollar preamps had fallen to the LSA.

I re-inserted the LSA into my system and left it there. Sure enough, I finally had to admit the LSA bettered my Supratek (which, by the way had been considerably improved with a DACT attenuator, V-Caps, better wiring, WE 350Bs, etc.)

In truth, the LSA was only very, very slightly better than my Supratek, but wow it is so much more user friendly without the hassle of tubes.
pubul57 OP
3,712 posts
 
Since I asked the question in terms of absolutes (Best)I repeat what I said early on - it is silly to speak of any piece of gear that way, and there are obviously many (some?) world-class line stages out there some which you or may not prefer to the LSA - why there isn't only one product on the market afterall. I now wish I had names this, LSA, Best Sound per $$$ Ever? - I think there would be much debate about that. The only problem is I don't think it is fair to make reference to it simply in terms of value for $$$, it does it a disservice to couch it that way - it is simply a very, very fine linestage that will suprisingly compete, and for some, surpass, many highly regarded linestages regardless of cost. In other words, worth auditioning no matter what you circumstances, and a must audition if you have limeted funds.
pubul57 OP
3,712 posts
 
I wish I would check my spelling. Of course I meant to say "I think there would NOT be much debate about that"
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